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Simple way to multiply big numbers watch!

metacafe.com — this counting-based technique lets ANYONE multiply big numbers together without a Calculator. It uses lines with Representative multitudes of the value of the digits to criss-cross, forming a plaid-like pattern, one then adds the number of intersections in certain crossing points to get the product of two numbers, no matter how big...F'ing awesome!

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  • rgodfrey, on 10/12/2007, -0/+80Kind of a cool representation of what you're doing with normal manual multiplication anyway, although I don't think it's any faster, and it gets a little unwieldy with high-digit values. I am trying to figure out how to adapt this into a bar bet.
    • gr8one, on 10/12/2007, -6/+28So that's how autistics do it....

      /kidding
    • mrASSMAN, on 10/12/2007, -2/+20"So that's how autistics do it...."

      I have to admit I was thinking the same.. this is pretty ingenious. This is probably a better method for some types of minds.
    • jonathantneal, on 10/12/2007, -2/+16The bar bet is "I bet you I can show you the correct answer to any complex multiplication problem without ever doing any multiplication, and only drawing lines and dots". The trick will be that you count the dots and add them up. It might not be the next big hit though.

      And, you'll look like a nerd, but the wise man spins this to his favor by tying it to some faux aspiration, like "Before I worked Pizza delivery, I had a scholarship to Cal State for Math, but I was too much into partying. Well ... *sigh* now I've wised up". Yea, make it sound real sentimental, women love that :)
    • D4r7h3v1l, on 10/12/2007, -0/+6I just use my slide rule watch to get an approximation. If I need accuracy, I can use paper or a calculator.
    • mwosh, on 10/12/2007, -3/+67Who the hell writes a nine like that?
    • resplence, on 10/12/2007, -14/+5I do.
    • rtini, on 10/12/2007, -2/+10This is classic. Whenever you try to "simplify" multiplication, you end up doing extra "simple" work to compensate for not knowing your single-digit multiplication tables.

      In this method, rather than just "remembering" what products of single digit numbers are, you can count the intersection points of a bunch of lines. Which is easier: drawing out and counting the intersection points of a 9 * 8 grid of lines to get 72, or looking at 9 * 8 and instantly recalling that it is 72?

      If you take the small amount of effort and time to memorize your single-digit multiplication tables, you'll save yourself lots of work for the rest of your multiplying days.

      This reminds me of typing: you can either learn touch-typing or waste tons of time looking for each key. My friend and I joked about making a special keyboard for folks who didn't want to learn touch typing; all the keys would be laid out a-z alphabetically, in two or three rows. It would save a lot of "hunt" time from the "hunt and peck" approach to typing. You could go from 3 words per minute to maybe 10!
    • superal1394, on 10/12/2007, -0/+2ok, so, long multiplication is DEFINATELY faster.

      probably also because I can rail off the times table for 2 through 9
    • hobbers, on 10/12/2007, -0/+0"If you take the small amount of effort and time to memorize your single-digit multiplication tables, you'll save yourself lots of work for the rest of your multiplying days."

      Yep. I do this all the time in my head. I can do any xx * xx fairly easily now. I haven't tried xxx * xxx much yet. And once you do it more, you start recognizing patterns and developing your own little routines for certain sets of numbers. I've almost gotten to the point where I can even do division as well and give you answers out to a couple decimal places. This has actually been useful in real life too. One instance was when I was cruising down the highway at 80 mph and the road sign said my exit was 11 miles away - a quick head calculation and I knew I was 8.25 minutes away. It didn't actually help me though, because I was still going to be late, heh.
  • NeMeSiS187, on 10/12/2007, -1/+77try 999x999! Then it's not a simple way anymore! :P
    • physep, on 10/12/2007, -10/+4its purpose is to be a quick way to multiply small X mid & mid X small INTs not much more
    • transeunte, on 10/12/2007, -4/+10Not as quick as the usual way and the good ol' calculator, but definitely more... fun.
    • Haroldx, on 10/12/2007, -16/+2haven't you guys ever heard of the FOIL method.. ?
    • e144539, on 10/12/2007, -0/+7I would have opted for a harder example
      with that I'd just say
      999x1000 - 999x1
      999000 - 999
      998001
    • nofxjunkee, on 10/12/2007, -0/+2yeah, in the case of 999x999 it's easier without drawing the lines but even then I can use the line method without drawing it all out. there will be 27 lines in each direction, with 9 areas where the lines intersect for each pair of digits that are multiplied. At each intersection there are 81 points (6 pairs of 9x9), so you get:

      81, 81*2=162, 81*3=243, 162, 81

      work right to left carrying anything over 9 and you get:
      1*81, carry the 8, leaves 1.
      10*170, carry the 17, leaves 0.
      100*260, carry the 26, leaves 0.
      1000*188, carry the 18, leaves 8.
      10000*99, is 990,000.

      =998001, final answer.

      But then again I'm not as visual as some so it might be easier for someone to draw the 54 lines and all that.
  • mikewhalley, on 10/12/2007, -2/+15I've just tried 487679 x 38241 and sure it doesn't hurt your brain as much as long multiplication but my eyes hurt instead. I'm going to be seeing lines for the rest of the day now!
    • junkmail02, on 10/12/2007, -19/+2how did you go through 10th grade geometry?

      -z00k
    • leo2791, on 10/12/2007, -2/+2did it work?
      were you able to get the right answer even with all the complications?
      (not an insult to you, just asking)
  • comradeTJH, on 10/12/2007, -9/+1much fun with 9999 x 9999 ;-)
  • SuperMank, on 10/12/2007, -8/+20"ANYONE"? It's so much simpler just to use the normal method:

    21
    x13
    063
    210
    273

    • physep, on 10/12/2007, -1/+12This method is not about ease of use, its about multiple representations of a solution.
    • kdrlx, on 10/12/2007, -0/+8much better than those freakin lines !!! i ll say ..
    • ektar, on 10/12/2007, -0/+9If it's not about ease of use then the submitter shouldn't have used the term "Simple way."
    • artgon, on 10/12/2007, -1/+17@ektar

      Absolutey. The title says "*SIMPLE* way to multiply *BIG* numbers." This method is niether simple nor is it effective for big numbers.
    • mizuhri, on 10/12/2007, -4/+2I agree. I tried a big number and it didn't work. It's much easier to just do it in your head or write it on paper. If you need a calculator to multiply 2 numbers then I don't think the lines will help.
    • leo2791, on 10/12/2007, -0/+2i should not have used simpler, it was slightly inaccurate but sounded better,
      i intended it to be easier for people who dislike/can't multiply

      and the only reason it didnt work with big numbers is because you were sloppy, no offense, the principal is sound, and if the practice finds any error, it is human
  • applejam, on 10/12/2007, -15/+0i ' m only test
  • wald, on 10/12/2007, -0/+38dugg for whoever came up with this. i agree its not any faster but boy who would have thought of this..
  • physep, on 10/12/2007, -3/+11I am a visual learner, and this concept of visualization of multiplication goes a lot further than what I've learned in in calc class. I only wish they could draw circles for division.
  • ajaddison, on 10/12/2007, -1/+1Wait till one of the digits is a zero, then try to keep in mind that you have to allow for the blank space and such.
    • mrASSMAN, on 10/12/2007, -0/+20use a dotted line..
    • JasonDelta, on 10/12/2007, -0/+5Yes, just use a dotted line to represent a 0. Then when you're using this technique with any number containing a zero, only two solid lines intersecting is counted, while a dotted line intersecting a solid line is null. However, on the far right the you will get only null values, except here you'll count the number of dotted lines present as 0's. Thus for something like 600x100 you'll get 6 solid line intersections on the far left corner, a bunch of null value intersections in the middle, and then there are 4 dotted lines present in the far right region, which means you'll have four 0's. Thus the answer is 60000.

      Basically though, this is little more than a cool trick, because most people can multiply far faster with a pen and paper using the traditional method than this one.
  • ilapko, on 10/12/2007, -2/+2Seriously, it would be much faster to just do it the good old way as SuperMank said. Watching that dude draw all those lines seemed kind of silly really. But I must say that it's cool that there is such a trick method but I'd never use it.
  • calabria, on 10/12/2007, -0/+5This is awesome. I have a sister who's a very visual person and has a hard time just looking at numbers and finding out meanings (She's also 10) I'll use this to give her a visual way of multiplying numbers. Thanks!
  • 1NutButtSlut, on 10/12/2007, -3/+3kinda cool process, but I think the method I learned in elementary school is better
    • physep, on 10/12/2007, -4/+1who says the way you learned in elementary school was right?
    • AWidgetIHaveNot, on 10/12/2007, -0/+2I wish I'd been taught Trachtenberg Speed Math at school. This is junk by comparison.
  • blackguest, on 10/12/2007, -10/+1metacafe.com = spam
  • transeunte, on 10/12/2007, -0/+3"It uses lines with Representative multitudes of the value of the digits to criss-cross, forming a plaid-like pattern, one then adds the number of intersections in certain crossing points to get the product of two numbers, no matter how big"

    This description just had me thinking "WTF?"
  • JHawk24821, on 10/12/2007, -0/+2Anyone know a way that us *uix digg'ers can take a look?
    • physep, on 10/12/2007, -1/+1ubuntu: 'apt-get install automatix2' from console; It helped me get a lot of the codecs i needed for media content..
    • muramasa, on 10/12/2007, -0/+1I was wondering that myself.

      Does it work with the beta flash plugin? I haven't bothered to install it because Youtube still works with the old one.
    • shoover, on 10/12/2007, -2/+1*uix? Am I confused, or do you mean *nix users?
    • haarp, on 10/12/2007, -0/+1Nope, beta 9.0 doesn't work. It's not like they're even trying, they just tell you to ***** off.
      asshats.
  • ragipy, on 10/12/2007, -1/+7Simple way to multiply big numbers = calculator?
  • qingshuo, on 10/12/2007, -3/+1Um...this visual method is pretty much identical to the way you did it in grade school. Look at the way he adds up the columns and carry the one, you'll be working with the exact same digits if you did it the old fashioned way, and you don't even have to count dots.

    And
    999x999
    = 1000x1000 - 1000 - 999
    = 10^3 x 10^3 - 1000 - 999
    = 10^(3+3) - 2000 + 1
    = 1 million - 2000 + 1
    = 998,001

    In the consulting/finance industry interviewers will gladly pull this on you and expect you to do it in your head.
    • jeaguilar, on 10/12/2007, -1/+1I'm not sure I agree with your second step. I think it should be:

      999x999
      = 1000x1000 - (2(1000)) +1

      How did you go from:

      = 1000x1000 - 1000 - 999
      and = 10^3 x 10^3 - 1000 - 999
      to this: = 10^(3+3) - 2000 + 1?
    • laplie, on 10/12/2007, -0/+1"and = 10^3 x 10^3 - 1000 - 999
      to this: = 10^(3+3) - 2000 + 1?"

      cause -999 = -1000 + 1

      -1000 - 999 = -1000 - 1000 + 1 = - 2000 + 1
    • dumbtech, on 10/12/2007, -0/+15Why not just do:

      999x999
      = 999x1000 - 999
      = 999000 - 1000 + 1
      = 998001
    • qingshuo, on 10/12/2007, -0/+1That's a great and even simpler method. The reason I do 1000x1000 first is so that I can get a clear "ballpark" of the answer right away which is 1 million. The truth is if you run into a 999x999 in a business situation, you are completely warranted to treat it like 1 million and obtain more granularity if necessary.
    • e144539, on 10/12/2007, -0/+1I knew someone else probably thought the same thing, I just hadn't read that far yet ;)
  • thearrow, on 10/12/2007, -0/+1Very cool
  • somerandomnerd, on 10/12/2007, -0/+6Very useful... So could someone please read the article and tell me what 78 x 23 is?
    • disti, on 10/12/2007, -1/+1Yes, it's 1794.
      Components: 14, 21+16=37, 24
      So:
      14
      _37
      +_24
      ----
      1794
  • rauz, on 10/12/2007, -0/+2Ah. "Liggande stolen" or "The lying down chair" as I suppose it could be translated.
    I think every Swede was taught this method since second or third grade...I had forgotten about it though.
    • physep, on 10/12/2007, -1/+1"The lying down chair"
      Kenneth Lay, Bill Gates, RobertT H. Cambell
      they come and ..leave
    • rauz, on 10/12/2007, -0/+1I didn't wanna say "Lying Chair" since that would be too weird :)
  • fba199, on 10/12/2007, -0/+9I wish I was in school right now. I would love to see my teacher's face with all these lines and dots all over my paper.
  • Battlecry, on 10/12/2007, -6/+3I really dislike metacafe videos.
    • picciano, on 10/12/2007, -2/+1Simple solution...don't click on them.
  • kdrlx, on 10/12/2007, -0/+7Try Vedic Math -- :)

    Here both are near 100, you can take the base as 50/10/500 anything ..
    88 * 98 =?
    88 - 12
    X
    98 - 2
    ---------
    86 - 24

    The 86 comes from subtracting crosswise: 88 - 2 = 86 (or 98 - 12 = 86)
    You can subtract either way, you will always get the same answer.
    And the 24 in the answer is just 12 x 2, you multiply vertically.

    So 88 x 98 = 8624
  • levyjl1988, on 10/12/2007, -2/+1amazing, I'll just try this... and to if it works, I wonder how... hmmmm
  • dysmas, on 10/12/2007, -0/+1weird, came across this on wikipedia the other day by clicking on random articles ... its a very old indian method,

    see en.wikipedia.org/wiki/shabakh

    and being able to make a decision of where to use this method and normal long multiplication requires some intelligence rather than following a routine,
  • CyberGhost, on 10/12/2007, -0/+1Cool but not practical,

    try 99 x 68 this method and the staditional method.
    • spudnic, on 10/12/2007, -0/+1Some numbers are always going to have easier ways to multiply them, point is that people who aren't very good at maths (a very large portion of the population) will find the method in this video a lot easier
  • billlyboobs34, on 10/12/2007, -0/+2"..but can it multiply ten ten ten ten ten ten...x ten ten ten ten ten ten ten..." - Ali G
  • Neme, on 10/12/2007, -1/+2If you take mathematics far in your academic life, you'll soon realize that being able to multiply numbers becomes irrelevant--it's the algebra that matters.

    This is interesting, but not that useful. As an astronomer, I'd rather just use my calculator, or a computer. :)
    • qingshuo, on 10/12/2007, -0/+1Yeah, computers do make life a lot easier, but I find it refreshing to do some mental math here and there to keep my brain cranking. Mental math is also a great way to ball-park figures in day-to-day life. Let's say you're reading an article about population growth and you get an absolute figure. To be able to immediately translate that figure into a % growth rate in your head would really deepen your comprehension of that particular article.
  • iwishuwerehere, on 10/12/2007, -2/+0Don't think that is really faster...
  • NyeruBaka, on 10/12/2007, -0/+2I think some of guys are missing a point in here.
    OF COURSE, you can do a math problem a lot faster in the way you learn in your school, but just think… how long have you been using the way you learn in elementary school and how many times have you use the way presented in the video… is just a matter of YEARS =)

    I tried some times the way in the video, and it can help a lot in some math problems, but please if you have a 2 digits math problem, just use your head, or if you have a calculator don’t even think in drawing lines and count dots.

    Very nice video man, bring another ones = )
  • dimension89, on 10/12/2007, -1/+0nvm
  • thydzik, on 10/12/2007, -0/+1this is quite amazing,
    very interesting, but not sure how useful it would be
  • SportBilly, on 10/12/2007, -0/+1Nice trick but seriously unless you're 10-15 years old its just going to slow you down when doing the proper complicated stuff. You gotta be quick in your head.
  • Zzzzz, on 10/12/2007, -2/+2Just try something simple (and obvious) like

    5000 x 10

    using this method, just does not *work* in my opinion. Basically I think the concept of introducing a zero into your values will cause problems using this method. But maybe I am wrong.
    • leo2791, on 10/12/2007, -0/+1you could draw one dotted line to remind yourself that there is no real digit there (as a place holder) , then not count its dots...that might be how they do it, (s)he never showed
  • h2oDomination, on 10/12/2007, -2/+0Dude...!
  • MagnumVP, on 10/12/2007, -0/+1It works for adding double digit numbers, but when you get into 837 x 692 it takes longer to draw up the lines and count the damn things than actually doing it the "Old Fashioned Way".
  • PharmaPhool, on 10/12/2007, -1/+2I'll stick with IEEE 754. Its super accurate but HARD!!! HARD AS HELL!!! Thats just how Math was in my day... you kids these days have it so EASY! And we used to walk five miles in the SNOW just to get to the school to learn the HARD MATH!!! bahhhhh!!
  • Oates, on 10/12/2007, -0/+2that was a neat looking 9...she wrote a 'g'
    • Sippi, on 10/12/2007, -0/+2I was wondering why her "9" looks like a "g" also. Anyone else out there do this?
  • ocpforme, on 10/12/2007, -0/+0This type of Math has been done before see Trachtenberg Math.

    http://hucellbiol.mdc-berlin.de/~mp01mg/oldweb/Tracht.htm
  • apollos, on 10/12/2007, -2/+1"This method lets ANYONE multiply big numbers together without a calculator..."
    Well, ANYONE who wants to learn and memorize a crazy line drawing system... don't forget to add the 1 from 14 over to the 8 on the left of it and then that makes 9 but keep the 4 for the next digit. Does anyone think this sounds any easier that using the 'simple' method we learned in 3rd grade? And not only that but ANYONE could do it!

    Also, if you need pen and paper I don't see at all how this is faster or simpler than using the method I've used for 16 years. I used paper and pen for that too.

    It's pretty cool but the title and description should have said, "Slightly innovative trick for solving math problems using lines that you may have already seen a variation of if you're a math nerd."
    • leo2791, on 10/12/2007, -0/+1yea but my title got 1840 diggs (joke)
      yours was more cynical
      all this method leaves is addition and we learned that in what...kindergarten??
  • whipnet, on 10/12/2007, -0/+1I Dugg this in 1984 on Compuserve! :)
  • yonnermark, on 10/12/2007, -0/+1say what you like about the OTHER method but this method allowed me to multiply two 4-digit numbers together for the very 1st time in my life. I'm not dumb, I just never picked up that other method despite many hours trying.
  • inmatarian, on 10/12/2007, -0/+2Clever, but I like using a method where I get inprecise figures and then "zoom" in as I call it. If anyone knows the name of this, I'd like to know it. It's kind of like the normal multiplication we all learned in school, but done with the leftmost digits first, as opposed to the right most.

    21 * 13

    20 * 15 = (20 * 10) + (20 * 5) = 200 + 100 = 300
    20 * 13 = 300 - (20 * 2) = 300 - 40 = 260
    21 * 13 = 260 + 13 = 273
    • apollos, on 10/12/2007, -0/+1Well described sir! I use the same method and with it you can actually do mental math with bigger numbers... no paper involved.
  • xcrypt, on 10/12/2007, -0/+1anyone else think that pen writes nice?
  • cr125er, on 10/12/2007, -0/+1It looks like a take on lattice multiplication which I still prefer over this line intersect counting method.
  • ForrestGump, on 10/12/2007, -0/+1HOLY *****!
    I wish I learned about this a few days ago when i was doing my Aptitude test... *****!
    I love it when things usefull to my life make it on digg.
  • apollos, on 10/12/2007, -0/+1"say what you like about the OTHER method but this method allowed me to multiply two 4-digit numbers together for the very 1st time in my life. I'm not dumb, I just never picked up that other method despite many hours trying."

    Which 4 digit numbers did you use? Because if it was something like 6893 x 4852, I can't imagine that the resulting spiderweb of lines was easy to decipher. Did it take you a long time?
  • Halgy, on 10/12/2007, -0/+1I don't know; I find it a lot easier to just do the long multiplication than count up all the dots.
  • leo2791, on 10/12/2007, -0/+1actually this reminds me of another method called the lattice method...
    http://mathforum.org/library/drmath/view/52468.html
    you set up the factors in a grid, then multiply individual digits together to get their products, then add those numbers together in segments made by diagonal lines,
    this line method is just a visual representation, its attraction is that you do no adding, not that its most convenient, the lattice method is easier, but you need to know your multiplication tables 1-9, since many of us are not in common use of pen and paper to solve math, and rely on a calculator, the lines are a handy representation
  • chaosss, on 10/12/2007, -0/+0very good. i love it.
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